Ukraine's European allies marshalled resources this week to provide the besieged country with air defences against drones and ballistic missiles. The European Union also announced an 18th round of sanctions designed to sever all remaining Russian energy imports, and proposed a fivefold increase in the common defence budget to boost EU defence research and procurement. European leaders convinced the United States to symbolically rejoin the 52-nation Ukraine Defence Contact Group coordinating defence donations, but not as a donor. It was the first such meeting attended by US Defense Secretary Pete Hegseth since February, when he told EU members that pushing Russia out of Ukraine's internationally recognised territory was unrealistic. As the ideological chasm between the EU and the US over Ukraine widened, Russia continued to pound Ukrainian defenders, making a few inroads.

This paper presents an empirical investigation of the relation between decision speed and decision quality for a real-world setting of cognitively-demanding decisions in which the timing of decisions is endogenous: professional chess. Move-by-move data provide exceptionally detailed and precise information about decision times and decision quality, based on a comparison of actual decisions to a computational benchmark of best moves constructed using the artificial intelligence of a chess engine. The results reveal that faster decisions are associated with better performance. The findings are consistent with the predictions of procedural decision models like drift-diffusion-models in which decision makers sequentially acquire information about decision alternatives with uncertain valuations.